This invention relates to surgical knives, and more particularly relates to a surgical knife having an attached, movable blade guard for protecting the knife blade.
One type of surgical knife that has been used in the past has a knife body with a cutting blade at one end of the body. The end of the body with the knife blade also has a portion that tapers down towards the knife blade to provide good visibility of the cutting tip. The blade is extremely sharp, and the extreme sharpness of the blades renders them hazardous when these knives are being passed back and forth during use in surgical operations. If the knife has already been used on the patient, then there is a potential danger of infection since the sharp knife can very easily cut a glove and the skin beneath the glove. Also, the actual cutting edges of these knives are very easy to damage, so that if a knife edge contacts another surgical instrument or an instrument tray or any other hard substance the blade can be damaged or ruined completely.
Accordingly, it seems desirable to provide a way to protect the integrity of the edge on the cutting blade. Such a protective structure should be economical and simple to manufacture, with a minimum amount of effort required to position the structure to protect the blade.
U.S. Pat. No. 4,576,164 to Richeson teaches a disposable micro surgical knife having a shroud that can be locked into a position protecting the blade. The shroud is in the form of a cylindrical sheath that moves axially along and around the knife body. In addition, the shroud has a plurality of projections which mate with a series of longitudinal and circumferential grooves formed in the exterior of the knife body. This arrangement of grooves on the knife body and projections on the shroud allow the shroud to be locked in two or three different axial positions on the knife body. In one position the shroud acts as an enlarged handle, and in a different position the shroud acts as a protective device for the blade and blade edges. However, if the shroud is damaged or slips off and is lost, then the knife body has undesirable grooves on its outer surface that may "feel" so different to a surgeon that it may prevent its use.
U.S. Pat. No. 4,414,974 to Dodson, et al. discloses a surgical knife with a shroud similar to the one disclosed by Richeson. However, this patent does not have a shroud with projections, and it does not have the longitudinal or circumferential grooves on the exterior surface of the knife body. Instead, this patent relies upon friction between some oversized portions of the body and the opening in the shroud for a frictional fit; in one axial position the shroud is retracted for use and in another axial position is in a blade protective position. However, this shroud may slip from its desired position if the frictional fit is inadequate, which may result from normal use and wear and tear.
U.S. Pat. No. 4,735,202 to Williams also teaches a disposable micro surgical knife having a blade guard. The blade guard is basically a cylindrical sleeve that has a longitudinal slot that extends to one end of the sleeve. The knife body has a small locking tab adjacent the forward tapered portion of the knife. The blade guard slides onto the knife body from the rear until the locking tab enters the longitudinal slot and the guard is rotated to be locked into place. Thus, the blade guard can be locked into a blade covering position and then totally removed from the knife body for use of the knife. However, this blade guard may be easily damaged or lost after removal, thereby defeating its purpose.
In a similar manner, U.S. Pat. No. 4,768,509 to Grosvenor et al. discloses a removable external blade guard. U.S. Pat. Nos. 3,706,106; 3,905,101; and 3,945,117 disclose other types of surgical knives having movable or removable blade protective structures. These knives suffer from the same or similar limitations as described hereinbefore.
These and other limitations and disadvantages of the prior art are overcome by the present invention, however, and an improved surgical knife with an improved attached, movable blade protector is provided for preventing damage to the knife blade of a surgical knife when it is not in use.